Magnetic disk drives are conventionally designed to store large volumes of data on a plurality of disks mounted on a spindle assembly. Typically, each disk includes two disk surfaces capable of storing data. On each disk surface, user data is divided into groups of sectors and stored in concentric circular tracks located between an outside diameter and inside diameter of the disk. Embedded servo information is recorded in servo sectors located in radially continuous narrow wedges along the disk surface.
As a result of the manufacturing process, defective locations may exist on the disk surfaces. To prevent these defective locations from being inadvertently accessed by an end user, a defect discovery procedure may be performed to locate these defects and mark them as defective before the disk drives are shipped. Defect discovery is often performed after the servo sectors have been written to the disk surfaces. A typical defect discovery procedure includes writing a known data pattern to all of the tracks of a disk surface and subsequently reading the data pattern from the disk surface. Defective locations are then identified by comparing the data pattern read from the disk surface with the known data pattern.
Following the defect discovery procedure, information indicative of the defective locations is stored in a defect list (often stored as a table). The defect list may then be used during formatting of the disk surface, wherein the defective locations may be mapped to data sector locations (e.g., cylinder number, head number, and data sector number (referred to as a “CHS address”)). Once identified in the defect list, the defective locations may not be used for storing data.
Unfortunately, as the storage capacity of disk drives has increased, so to has the process time required for the defect discovery procedure. This increased process time has in turn increased the cost of manufacturing disk drives.
There is therefore a need in the art for more rapid and efficient identification of defects in disk drives both during and after manufacturing.